Continuing effort has been directed toward the development of coatings suitable for use in applications such as printed circuit board bar-code labels, wave solder masking tapes, automotive labels and electrical insulation. Historically, bar-code label construction applications have been particularly troublesome from two standpoints: (1) a harsh manufacturing environment; and (2) a harsh handling environment--both necessitating a scratch and mar resistant top surface. Since the bar-code label is attached early in the manufacturing process, such environments include temperatures up to 300.degree. C.; UV exposure; solvent wash and vapor degrease using MEK, toluene, trichloroethylene, water, et cetera; acid etching with sulfuric acid, nitric acid, chromic acid, et cetera; wave solder and solder reflow; and vapor phase curing of surface mounted component adhesives.
Further, as to the handling environment, the bar-code label construction must be opaque to prohibit markings below the label from showing through and interfering with bar-code scanning. The top surface of the bar-code label must preferably be white to maximize contrast to the black bar-code ink. The top surface of the bar-code label must also be scratch and mar resistant to prevent markings from bar-code scanners and other handling hazards. These markings can interfere with the reading of the codes.
Bar-code label constructions presently available are problematic in that the top surface coatings are not entirely scratch and mar resistant to prevent markings caused as a result of the handling of the bar-code labels, particularly the use of the labels in combination with a bar code scanner. Thus, it is apparent that a need exists in the industry for a bar code label construction capable of withstanding the harsh environments associated with the manufacturing and the resultant handling of a bar code label construction.